Standing balance in archers: Stambolieva 2015

Ten young Bulgarian Olympic recurve archers, men with a mean age of 23 and more than five years of training three times a week, were compared with 15 untrained peers who went to the gym once or twice a week. Everyone stood still on a force platform, without a bow, for 30 seconds in four conditions: eyes open and closed, on a firm floor and on a foam cushion that makes the information from the feet less reliable. From the movement of the centre of pressure the authors derived the mean amplitude and mean velocity of sway, front to back and side to side.

The archers swayed less: the group effect was significant for amplitude (F = 34.42 front to back and 43.71 side to side, p < 0.001) and for velocity (F = 26.31 and 17.53, p < 0.05). Amplitude was smaller in every condition except one, standing on the firm surface with eyes open in the front-to-back direction. Closing the eyes made almost no difference in the archers. Foam increased sway in everyone, but in the archers amplitude rose significantly only with eyes closed, in the untrained group with eyes open as well. For velocity, the archers did better on the firm surface with eyes open and closed, while on foam the difference remained only with eyes closed, front to back. Mean values are given only in the graphs.

Participants stood with heels 3 cm apart, feet turned out at 30 degrees and arms by their sides, trying to stay as still as possible; with eyes open they looked at a red dot two metres away at eye level. Each trial lasted 30 seconds with 30 seconds' rest. The foam cushion measured 40 by 40 cm and was 15 cm high. The platform is a posturography system built by the researchers themselves, sampling every 10 ms with a 10 Hz filter. The data were analysed with a three-factor analysis of variance (group, vision, surface) and Newman-Keuls post hoc comparisons. The number of trials per condition is not given.

The position measured is not the shooting position: feet almost together, arms by the sides, no bow and no draw. So the study shows how archers stand still, not how they sway while aiming, and there is no link with score. It is also a comparison at a single point in time: that archery training is what makes people steadier, as the authors conclude, is an interpretation, since people who already balance well may simply stay in the sport longer. The role of the vestibular system is inferred from comparing conditions, not measured.

The sample is small and all we know about the archers' level is how many years they have trained. The standard deviations for height (0.51 and 0.71 cm) are too small to be plausible, and the text mentions consent co-signed by parents for participants aged 23. The amplitude and velocity values can only be read from the graphs, so the size of the differences cannot be taken from the text. This is a workshop paper, and it is not known whether it was peer reviewed.

The study adds a descriptive finding: archers with years of training stand more still than untrained peers, and lose little when they cannot see. The difference shrinks when the support becomes soft, that is when the information from the feet gets worse. For an archer it does not change how to train: it does not measure the shooting posture, it does not link balance to points and it does not show that balance exercises improve shooting. It is one of the pieces suggesting that postural control in experienced archers differs from that of non-archers, without saying how much it counts in the shot itself.